Closed-loop operation and control strategy for the Dual Active half Bridge AC-AC converter

Abstract

This paper presents the modeling and control study of an AC-AC Dual Active Bridge (DAB) converter for solid state transformer (SST) applications. The DAB converter under study consists of a full bridge converter on one side and a half bridge converter on the other, both with four-quadrant switches connected through a high-frequency transformer. The direct AC-AC connection reduces the conversion stages, adding advantages to the system such as greater reliability and efficiency. In addition, the half-bridge structure has a smaller number of active components, presenting advantages for operations in specific power ranges, besides exempting the use of capacitors in order to eliminate DC current in the transformer. The voltage control in one of the ports allows regulation and the control of the power flow according to the load demand, being a good option for the use in SSTs. In the end of the paper, experimental results are presented using a 600 W prototype voltage controlled in both 220 V ports.